Donald Trump surprised his audience a couple times during his acceptance speech at the Republican National Convention Thursday. He didn’t enter to any notable special effects. He remained calm and stuck to the TelePrompter for most of the speech.

But one time he strayed, ad libbing for a moment in the most unexpected way. In talking about the support he had received from evangelical voters, Trump got introspective.

“At this moment, I would like to thank the evangelical and religious community in general who have been so good to me and so supportive,” he said, adding “and I’m not sure I totally deserve it.”

It was so far from his signature unrelenting bombast. Normally, he’d just tout his poll numbers with evangelical voters, pat himself on the back, and move on, with little to no appreciation for those people or acknowledgement of how truly odd, even morally uncomfortable, their alliance is with the secular New York City businessman. His unscripted aside seemed to almost sheepishly nod to his own failings and suggest for a split second there might be something of which Donald J. Trump thinks he’s not worthy.

The question of the campaign has been and will continue to be, “Can Trump change or grow into a presidential presidential candidate?” That tiny moment was an exceedingly rare glimpse of what it would take to do that.